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H/F Series transmission limit

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Old 04-17-2018, 12:26 PM
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Default H/F Series transmission limit

I hate to clog up the DR forum with something that isn't strictly drag racing, but other forums have little activity and the H22/F22 is a bit of a neglected platform to begin with so information is either incomplete, scarce, or a decade old when talking about high hp H/F builds.

to you guys that have experience with the H/F transmissions in abusive/ high hp applications.... at what point do you start to see failures of the oem gearset/diff? I have a 5th gen prelude (2,750lbs currently) that is at 315whp/265wtq and currently have no issues whatsoever running a stock H23 trans. Im at a crossroad here where i really want to build my block (F22B DOHC) and push my STC Hunter as hard as i can on E85 which will likely land me in the 450-500whp/350-400wtq range... but I'm not in a position to spend (or waste) $5k to build the trans with a custom gearset and would likely abandon the platform if that's my only option.

The only relevant info I've found on this subject is from HT user "extralargenog" that swears on his mom's **** that these transmissions straight up explode and shred gears at 400wtq and above and that he has blown dozens of these transmission, which is just hard to get my head around when so many B series guys are scooting along at 600+whp without any issues at all. Any real life experience/ advice you guys have would be greatly appreciated as I'm just too scared to pull the trigger on this block and be picking up pieces of my transmission off the highway 2 days after i tune it. I feel like the weght of the prelude may play a part in this, im just not sure to what extent.

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Old 04-18-2018, 07:54 AM
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Default Re: H/F Series transmission limit

Keep in mind, his car is a heavy Accord, on big drag radials and he beats the **** out of it, at 750+ WHP.

I have seen a couple of H cars in the 5-650 range that have held up well, but they have been lightened 4th gen Preludes, or Civics. I don't make that much power, but my only issue has been 2nd gear syncros for some reason, and almost all of my use is on slicks, and shifting at 8500 or so rpm.

If the transmission cost if you do end up needing to upgrade is keeping you from moving on with your build though, trust your gut and pocketbook.
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Old 04-18-2018, 08:27 AM
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Default Re: H/F Series transmission limit

5-650 hp or tq? Like you, i have seen a couple civics do it, just no 5g preludes... which begs the question of if no one has tried, or everyone just fails and gives up (which seems more likely). The other issue I'm having is even if i did decide to go with a pricey gearset, im unaware of one that had held up for people. Are you aware of any that are reliable?
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Old 04-18-2018, 11:29 AM
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Default Re: H/F Series transmission limit



Heavier the car the harder it is on the transmission. A EG Civic 2200 lbs vs 3200 lb 4 door Accord going to have different limits. But the rule of thumb is its a Gamble over 450 ft lbs of torque.... I am currently 501 whp and 385 ft lbs of torque on pump 17 psi on carbon synchro m2b4. Torco mtf.

Saenz Gearset is one of the few Gear Sets that can hold the power. A friend put down just about 600 ft lbs of torque on one. Dyno. The gearing is pretty short and 4.0 fd is a must or even lower. Need a good LSD aftermarket as well. Its around $3k+ for gear set... then install by prof.

If you are just looking around 500 whp you should be fine... probably wont reach 400 ft lbs of torque... you also need to know how to launch the car at the track etc. pre loading etc.... Some people just go bonza at the track no preloading and too high rpm and snap diffs and axles easy...
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Old 04-18-2018, 11:59 AM
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Default Re: H/F Series transmission limit

That picture is equal parts funny and depressing lol. So you haven't had any issues shredding gears at your power level? have you personally seen these hold up at 400tq in a heavy chassis? My knowledge on transmissions is limited.... your synchros don't actually save the gear itself from any damage right? Is the recommendation for the LSD related to performance or the fact that we also have weak diffs in these trans? If I'm pushing it near 400wtq would it be necessary for me to get away from Honda MTF? Don't mean to 20 question you, just want to know what I'm getting myself into.

honestly, if it were going to be the difference between dealing wth trans problems or not, i would quit going to the track altogether and keep it solely on the street. I love these engines and the prelude itself, i just don't want to box myself into a corner down the road. If you think ill be alright at 500whp/350-400wtq then ill settle down and stop worrying about it so much. I don't see myself taking the power level far beyond that in this car (but we all say that in the beginning).
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Old 04-18-2018, 12:14 PM
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Default Re: H/F Series transmission limit

Synchros wont save gears. There is no reason to take it apart if shifts fine. No will not help transmission much. Diffs aren't really weak... for most 400-450 ft lbs of torque is a lot of power... we are lucky transmission is even that strong enough from the factory....I would probably switch to Torco MTF... can't really go wrong... it will take the abuse better...

Like I said on the forums on fb...80% of people are having gear issues is at 450 ft lbs torque.... last one recall was like 475 ft lbs....

what you can do to help things is to make sure to have boost by gear. This will put less strain till you get speed going... then it is lesser concern to damage... average 1st gear 8-10 psi, 2nd gear 10-12 psi, 3rd 15 psi, 4th and 5th for me is 17 psi. If you could alter it you would want torque to ramp up higher in RPM... versus down lower....
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Old 04-18-2018, 12:37 PM
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Default Re: H/F Series transmission limit

Thanks a ton, that's good info. I hadn't considered how boost by gear could aid in longevity. Do you do that for that very reason or does that last 2psi blow the tires off in 3rd? I have a relatively responsive turbo so i probably won't be able to get away from torque coming in early on in the powerband but I'll for sure utilize BBG if that helps. Is it just the nature of all that torqe coming on really quick in the early gears that puts so much stress on the system? I'll also switch to Torco immediately if Honda MTF isn't up to the task. I need to get on fb so i can see these discussions because these forums are just dead these days.

and yeah, i suppose 400wtq IS a lot... being used to the power just skews perception. When i first drove my prelude with 315whp i thought it was a rocket....lol a year later and it feels like a minivan pulling a trailer.
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Old 04-18-2018, 01:36 PM
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Default Re: H/F Series transmission limit

Boost By Gear is important...I mean if someone is going crazy and is doing 20 psi in 1st and 2nd and all the gears... that puts quite a strain down low plus wont be as quick as right boost by gear needed to scoot....
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Old 04-28-2018, 12:33 AM
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Default Re: H/F Series transmission limit

Use Torco RTF, not MTF. The trans will be much happier.

If you can't or don't want to spend 5k+ on a trans build, don't exceed 400tq.
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Old 04-28-2018, 06:45 PM
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Default Re: H/F Series transmission limit

I put 380-400wtq through a 300k mile H23 trans for about 8 months. However I never launched it hard or power shifted. I was basically babying it because I knew it could have popped at any time. Motor is long gone but the trans is still going in my car and it gets driven almost daily. Used nothing but GM synchromesh.
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Old 04-30-2018, 07:21 AM
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Default Re: H/F Series transmission limit

At the power level you are posting about, just don't use a heavy duty axle. at only 450-500whp, I wouldn't worry about busting the trans. A cuff will help keep it safe but then you lose 5th gear.
There is a huge difference between that and 750+whp and the torque associated with that power on a 2.2L.
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